(BSS/AFP) - British Prime Minister Andy Burnham on Wednesday said there were "strong indications" Iran was involved in suspicious activity at a UK airbase that triggered a major security incident this weekend.

"There are strong indications that Iran played a part in what happened over the weekend at RAF Fairford," Burnham told the BBC, referring to Sunday`s bomb scare near the airbase in southwest England, which is used by the US military in its war against Iran.

"Of course it remains an ongoing, complex, and serious police investigation," said Burnham.

Iran`s embassy in London earlier said it "categorically rejects and strongly condemns" speculation it was involved in the incident, while Foreign Minister Abbas Araghchi posted on X that Burnham was "barking up the wrong tree".

Police said on Tuesday that no explosives were found at the scene. The nature of the threat has not been explained by officials.

Burnham`s comments are the first official confirmation from UK authorities that Iran may have had a hand in the incident, which saw three white vans appearing to head towards RAF Fairford in the early hours of Sunday.

A local resident who rang the police said she saw a group of masked men near the vans, which were blocking a road in a village next to the military base.

- Growing confusion -

The case was plunged into confusion when UK police released on bail five British men it had arrested on Sunday on suspicion of explosives and terrorism offences.

After three days of investigations, including using a bomb disposal team, police said Tuesday they had found no explosives in the vehicles, but they had retrieved a "quantity of petrol".

Then on Wednesday, The Times newspaper reported that the incident had been foiled after one of the five suspects tipped off the police before the group was apprehended.

US President Donald Trump and his Secretary of State Marco Rubio had previously indicated that intelligence bodies were aware of the suspects and that a foreign state could be involved, but UK officials had not weighed in.

"We have been waiting to confirm what we could say, but we can now confirm our belief that Iran played a part," Burnham told Sky News.

Speculation was rife that Iran or another hostile state could have been involved, after Tehran previously warned London against allowing its military bases to be used by Washington.

Britain gave the US the greenlight to use RAF Fairford for defensive strikes against Iran, drawing Tehran`s ire and unease from some residents in the Gloucestershire countryside where the base is located.